1. Field of the Invention
This invention relates to a tape cassette for use with a tape recording and/or reproduction device and, more particularly to a tape cassette including a housing having a forward zone adapted to receive the magnetic head of the device, a pair of spools arranged side by side in the same plane, and a magnetic tape extending along said forward zone from one of said spools to the other, and finally, guiding means for the tape.
2. The Prior Art
There have been developed and are known extremely compact tape recorders. The cassettes for use with such tape recorders are extremely small and commercially known as "mini-cassettes" or micro-cassettes. The magnetic tape used in such cassettes has an extremely small width (below 5 mm).
In order to obtain the desirable quality of reproduction with such devices, it is extremely important that accurately defined guidance of the tape within the cassette in relation to the magnetic head of the device be achieved.
Since all component parts of both the cassette and the recorder, such as the guiding means, the spools, the magnetic head and the like, are of extremely small size, it is particularly difficult to provide for the tape to be moved with sufficient stability. Besides the smallness of the cassette, the recorder and the component parts thereof, the fact should be taken into consideration that in the case of a four-channel stereo program the information content will have to be accommodated within one-half of the width of the extremely narrow tape. When a so-called direct four-channel system is used, it is necessary to accommodate four tracks within one-half of the width of the tape. When use is made of a so-called matrix four-channel system there will have to be accommodated within one-half of the tape width two tracks whose information content is interlinked by a phase matrix. It is particularly in the latter case that it is necessary for the achievement of a satisfactory quality of recording and reproduction to keep the narrow tape free of any mechanical vibrations as it is guided past the magnetic head of the recorder.
In order to obtain improved and well defined tape guidance in cassettes of the small size mentioned, it has been proposed in U.S. Pat. No. 3,735,940 to provide the tape guiding arrangement with a guide roller having a convex peripheral surface such as to produce a self-centering action of the tape in relation to the guide roller. However, this known arrangement does not provide for accurately defined guidance of the tape since even in the presence of a convex guide surface the tape is allowed to migrate upwardly or downwardly within limits until it comes into contact with suitable shoulders.
In U.S. Pat. No. 3,677,494 there have been proposed oblique guiding means which, however, are intended to guide the tape from the winding plane of one spool to the winding plane of the other spool which is at a higher elevation than the first winding plane.
It is an object of this invention to provide, particularly in the case of the well-known mini- or micro-cassettes, for the tape to be guided in relation to the magnetic head of the recorder in such a manner as to preclude vibrations of the tape and to maintain the tape at an accurately defined level.